The desire to find improved polymeric compositions which can be used for specific medical and environmental applications is ever present. There is a continuous search for new, improved biodegradable polymers to provide enhanced materials which are biocompatible, have good bioabsorbtive/biodegrable properties, appropriate mechanical and physical properties and related structural characteristics which find use in the prescribed application. Materials which provide superior characteristics as well as flexibility in formulation and manufacture are especially desirable.
Early biodegradable/bioabsorbable polymers focused on polylactic and/or polyglycolic acid homopolymers or copolymers which were used primarily in bioabsorbable sutures. These early polymers suffered from the disadvantage that the polymers tended to be hard or stiff and often brittle with little flexibility. In addition, the kinetics of their degradation tended to be slow in certain applications, necessitating research on polymers with faster degradation profiles.
A number of other copolymers utilizing lactic acid, glycolic acid, .epsilon.-caprolactone, poly(orthoesters) and poly(orthocarbonates), poly(esteramides) and related polymers have been synthesized and utilized in medical applications with some measure of success. The polymers tend to be limited, however, by disadvantages which appear in one or more of the following characteristics: flexibility, strength, extensibility, hardness/softness, biocompatability, biodegradability, sterilizability, ease of formulation over a wide range of applications and tissue reactivity.
Recent investigative attention has centered on the production of ACA triblock polymeric compositions which are derived from blocks of poly(oxy)alkylene and polyhydroxycarboxylic acids. These formulations, among others have exhibited favorable characteristics for use to reduce and/or prevent adhesion formulation secondary to surgery and other medical applications.